In recent years, diabetics are recommended to make daily self-control by measuring the variations in blood sugar level by themselves. For the measurement of blood sugar level, a blood component measurement device has been put into practical use, in which a test paper impregnated with a reagent capable of coloration according to the quantity of glucose in blood is mounted, blood is supplied to the test paper to effect coloration, and the degree of coloration is optically measured to thereby determine and display the blood sugar level. In addition, a blood component measurement device using an electrochemical sensor has also been put to practical use.
When a patient samples his own blood, a puncture needle capable of being advanced and retreated in the axial direction thereof is instantaneously projected by applying a repelling force of an elastic body to the puncture needle, whereby the patient's skin is punctured by the puncture needle and a minute amount of blood is let bleed. Such a puncture needle tip is integrally provided with a measurement member such as a test paper and mounted to a blood component measurement device, and measurement is conducted by use of the device, whereby a puncturing step and a measuring step are performed automatically and continuously.
For example, such a blood component measurement device as above-mentioned is disclosed in Japanese Patent Laid-open No. 2004-33438 or Japanese Patent Laid-open No. 2004-33439, in which a puncture member having a needle capable of being advanced and retreated along the axial direction is provided at the substantially center of a casing, and a tip-formed sensor is disposed at such a position as to approach the needle when the puncture member is displaced toward the human body side. The sensor is provided to be spaced by a predetermined distance in a radial direction of a circle, with the needle as a center of the circle, and, when the needle is let puncture the skin of the human body, the blood bleeding from the skin flows toward the sensor side, to be led to the test paper.
In addition, another blood component measurement device is disclosed in U.S. Pat. No. 6,866,675, in which a puncture needle is passed through the inside of a blood sampling capillary tube, and a mouth of the capillary tube is disposed directly above a punctured part of a skin so that blood is sampled from the punctured part and served to measurement.
Meanwhile, according to the related art as above-mentioned, the needle for puncturing the skin and causing blood to flow out and a blood introduction port for leading the blood having flowed out to the measurement unit are spaced by a predetermined distance from each other. More specifically, the needle of the puncture member is disposed on the center axis of the blood component measurement device, and the blood introduction port is spaced by a predetermined distance from the axis. As a result, the punctured part of the skin where blood is let flow out by the needle and the blood introduction port for guiding the blood are spaced from each other, so that a large amount of blood must bleed until the blood comes into contact with the blood introduction section, in the process of guiding the blood to the measurement unit.
Besides, according to the related art as above-mentioned, the configuration wherein the puncture needle is disposed in a capillary tube causes difficulties in design, layout or the like of the measurement unit for measuring a component of blood, and makes it difficult to achieve the desired measurement by use of a measurement device simple in configuration.